One thng to keep in mind is the Build out level on the DSX-1 port on your TSU600

double check your equipment to amke sure it can handle the level comming from the DSX-1.

if i recall it is -7db by default

I went through fits the first time I programmed a tsu600 and took a few late nite calls to adtran tech support which is BAR NONE the best i have ever seen, they will support there, doesn't matter if you bought it new or used, they stand behind it 100%